High pressure reaction vessel for growing diamond on diamond seed and method therefor

Abstract

Means are described for suppressing spontaneous diamond nucleation in the vicinity of diamond seed material located in reaction vessel construction used in the growth of diamond by the process disclosed in U.S. Pat. No. 3,297,407--Wentorf, Jr. In assembly of the reaction vessel a portion of the lower surface of the plug of catalyst-solvent metal is disposed in contact with the diamond seed material. Preferably all of the balance of the lower surface area of the catalyst-solvent plug adjacent the seed material is covered with a disc or layer of a material different from the catalyst-solvent metal employed and selected from a list of specific materials that suppress diamond nucleation.

What I claim as new and desire to secure by Letters Patent of the United States is: 
     
       1. In a reaction vessel for introduction into the reaction volume of a high pressure, high temperature apparatus, said reaction vessel constituting an assembly of interfitting elements for enclosing diamond seed material and a source of substantially pure carbon separated by a mass of metallic catalyst-solvent for the diamond-making reaction disposed therebetween so as to provide a predetermined temperature gradient between said diamond seed material and said source of carbon under operating conditions of pressure and temperature above the graphite-to-diamond equilibrium line on the phase diagram of carbon, said diamond seed material and said source of carbon being located in separate regions of said reacion vessel such that under said operation conditions said diamond seed material will be at a temperature near the minimum value of temperature for said temperature gradient and simultaneously said source of carbon will be at a temperature near the maximum value of temperature for said temperature gradient, the improvement comprising: (a) a layer of diamond nucleation suppressing material disposed in direct contact with the underside of the mass of metallic catalyst-solvent, said nucleation suppressing layer being made of a material different from the catalyst solvent and being a metal capable of holding back diamond nucleation at least until the seeded growth becomes quite large, well formed and capable of accepting the full carbon flux selected from the group consisting of cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium, and alloys of the preceding metals, said metal capable of holding back diamond nucleation thereby suppressing unwanted spontaneous diamond nucleation;   (b) the diamond seed material also being disposed in direct contact with the underside of said mass of metallic catalyst-solvent through said nucleation suppressing layer; and   (c) said nucleation suppressing layer and said mass of metallic catalyst-solvent being of different materials in any given reaction vessel construction.   
     
     
       2. The improvement recited in claim 1 wherein the diamond seed material is a single crystal. 
     
     
       3. The improvement recited in claim 2 wherein the diamond seed is oriented with a cube face thereof in contact with the mass of metallic catalyst-solvent. 
     
     
       4. The improvement recited in claim 1 wherein the diamond seed material consists of single crystals at spaced locations. 
     
     
       5. The improvement recited in claim 1 wherein the nucleation suppressing layer is metallic and the diamond projects through a hole therein and is spaced from the edges of said hole. 
     
     
       6. The improvement recited in claim 1 wherein the nucleation suppressing layer is cobalt. 
     
     
       7. In the process for producing diamond material wherein a reaction vessel containing (a) diamond seed material and (b) a source of carbon separated by (c) a mass of catalyst-solvent material for the diamond-making process is subjected to simultaneous pressurizing and heating at a pressure and temperature in the diamond stable region of the phase diagram for carbon; said source of carbon, said catalyst-solvent material and said diamond seed material being disposed in said vessel so that during said pressurizing and heating a predetermined temperature gradient exists between said diamond seed material and said source of carbon such that said diamond seed material is at the minimum value of temperature for said temperature gradient while said source of carbon is at the maximum value of temperature for said temperature gradient, the improvement of inhibiting diamond growth in the peripheral vicinity of said diamond seed material at least until substantial diamond growth has developed from said diamond seed material by the use of a layer of nucleation suppressing material, different from said mass of catalyst-solvent material, disposed in contact with the underside of the mass of catalyst-solvent material in the area peripheral to said diamond seed material, said nucleation suppressing material being a metal capable of holding back diamond nucleation at least until the seeded growth becomes quite large, well formed and capable of accepting the full carbon flux selected from the group consisting of cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium, and alloys of the preceding metals, said metal capable of holding back diamond nucleation thereby suppressing unwanted spontaneous diamond nucleation the diamond seed material being in direct contact with the mass of catalyst-solvent to allow unrestricted diamond growth from the seed material freely into the mass of catalyst-solvent under the operating conditions, whereby diamond growth greater than about 1/20 carat is produced. 
     
     
       8. A process for the production of diamond material comprising the steps of: pressurizing a reaction vessel containing a diamond seed material and a source of carbon, separated by a mass of catalyst-solvent material to a pressure in the diamond stable region of the phase diagram for carbon; while simultaneously heating said reaction vessel in such a manner to create within said vessel a temperature gradient in said diamond stable region such that the diamond seed material is at a temperature near the minimum temperature of said gradient and said source of carbon is at a temperature near the maximum temperature of said gradient, whereby a temperature gradient is created between the said seed material and carbon source; maintaining the diamond seed material in contact with the mass of catalyst-solvent material to allow unrestricted diamond growth directly from the seed material freely into the carbon saturated catalyst-solvent mass and inhibiting diamond growth with the use of nucleation suppression material, different from said catalyst-solvent material, said nucleation suppression material being a metal capable of holding back diamond nucleation at least until the seeded growth becomes quite large, well formed and capable of accepting the full carbon flux selected from the group consisting of cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium, and alloys of the preceding metals, and located in the peripheral vicinity of the diamond seed material under the operating conditions until a substantial diamond growth pattern has been developed from said seed material, said metal capable of holding back diamond nucleation thereby suppressing unwanted spontaneous diamond nucleation whereby diamond growth greater than about 1/20 carat is produced.   
     
     
       9. A process as defined in claim 8 wherein said inhibiting step includes the step of using said nucleation suppression material in the peripheral vicinity of said seed material for a distance of at least 50% greater than the lateral growth dimension of the diamond to be grown. 
     
     
       10. A process as defined in claim 8 wherein said seed material is a single crystal. 
     
     
       11. A process as defined in claim 8 wherein said seed material includes a plurality of single crystals at spaced locations. 
     
     
       12. A process as defined in claim 8 wherein said seed material, carbon source and catalyst-solvent are positioned in stacked planar relationship within said reactor vessel. 
     
     
       13. A process as defined in claim 12 wherein said inhibiting step is performed by interposing a nucleation suppressing layer in the reaction vessel in contact with said mass of catalyst-solvent and circumjacent said seed material prior to said pressurizing and heating steps. 
     
     
       14. A process as defined in claim 13 wherein the suppression layer is a metallic disc and defines a circular hole through which the seed material projects, the ratio of the diameter of the hole to the largest dimension of the seed material being in the range of 1.5:1 to 5:1. 
     
     
       15. A process as defined in claim 13 wherein said suppression layer is from about 1 to about 10 mils in thickness. 
     
     
       16. A process as defined in claim 10 wherein said nucleation suppressing material melts at a temperature higher than said mass of catalyst-solvent and is a material different from said mass. 
     
     
       17. A process as defined in claim 7 wherein said layer is a nucleation suppressing layer which melts at a temperature higher than said mass of catalyst-solvent and is a material different from said mass. 
     
     
       18. A process as defined in claim 7 wherein said diamond seed material is a single crystal. 
     
     
       19. A process as defined in claim 7 wherein the diamond seed is oriented with a cube face thereof in contact with the mass of catalyst-solvent. 
     
     
       20. Apparatus for the production of diamond materials comprising: a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent; means for pressurizing said vessel to a pressure in the diamond stable region of the phase diagram for carbon; means for heating said vessel, contemporaneously with pressurization, in such a manner to create a temperature gradient in said diamond stable region within said vessel such that the diamond seed material is at a temperature near the minimum temperature of said gradient and said source of carbon is at a temperature near the maximum temperature of said gradient, whereby a temperature gradient is created between said seed material and carbon source; the seed material being in direct contact with the mass of catalyst-solvent material to allow unrestricted diamond growth from the seed material freely into the carbon saturated catalyst-solvent mass and means, different from said catalyst-solvent, for inhibiting spontaneous diamond nucleation in the vicinity of the seed material under the operating conditions of the diamond making process until a substantial diamond growth pattern has developed from said seed material, whereby diamond growth greater than about 1/20 carat is produced, said diamond nucleation inhibition means being different from said catalyst-solvent and being a metal capable of holding back diamond nucleation at least until the seeded growth becomes quite large, well formed and capable of accepting the full carbon flux selected from the group consisting of cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium and alloys of the preceding metals, said metal capable of holding back diamond nucleation thereby suppressing unwanted spontaneous diamond nucleation. 
     
     
       21. An apparatus as defined in claim 20 wherein said diamond seed material is a single crystal. 
     
     
       22. An apparatus as defined in claim 20 wherein said seed material, carbon source and catalyst-solvent are arranged in stacked relationship within said vessel. 
     
     
       23. An apparatus as defined in claim 20 wherein said means for inhibiting extends for a distance of at least 50% greater than the lateral growth dimension of the diamond to be grown. 
     
     
       24. An apparatus as defined in claim 20 wherein said inhibiting means is a metallic disc with an opening therein, said seed material being located within said opening, the ratio of the lateral dimension of said opening to the largest dimension of the seed material is in the range of 1.5:1 to 5:1. 
     
     
       25. An apparatus as defined in claim 20 wherein said inhibiting means is a nucleation suppression layer, which melts at a temperature higher than said mass of catalyst-solvent and is a material different from said mass, said layer being positioned in the peripheral vicinity of the seed adjacent the catalyst-solvent. 
     
     
       26. In an apparatus for the production of diamond material comprising: (i) a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent for the diamond-making process;   (ii) means for heating said vessel to a temperature in the diamond stable region of the phase diagram for carbon and to create a predetermined temperature gradient in said reaction vessel such that said diamond seed material can be maintained at a temperature near the minimum value of temperature for the temperature gradient at substantially the same time said source of carbon is at a temperature near the maximum value of temperature for said temperature gradient; and   (iii) means for applying high pressure for operating said reaction vessel in the diamond stable region of the phase diagram for carbon; the improvement comprising:   (iv) a layer in said reaction vessel adjacent said mass of catalyst-solvent, said layer being a nucleation suppressing layer different from said mass of catalyst-solvent and having at least one opening therein between said diamond seed material and said mass of catalyst-solvent said seed material projecting through said hole into contact with said mass of catalyst-solvent, said nucleation suppressing layer being a metal capable of holding back diamond nucleation at least until the seeded growth becomes quite large, well formed and capable of accepting the full carbon flux selected from the group consisting of cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium, and alloys of the preceding metals, whereby diamond growth proceeds from said seed material, with said metal capable of holding back diamond nucleation thereby suppressing unwanted spontaneous diamond nucleation adjacent the seed material and diamond growth greater than about 1/20 carat is produced.   
     
     
       27. An apparatus as defined in claim 26 wherein said diamond seed material is a single crystal. 
     
     
       28. An apparatus as defined in claim 27 wherein the diamond seed is oriented with a cube face thereof in contact with the mass of catalyst-solvent. 
     
     
       29. An apparatus as defined in claim 26 wherein said nucleation suppressing layer is cobalt. 
     
     
       30. An apparatus as defined in claim 26 wherein said catalyst-solvent is a Ni-Fe alloy and said nucleation suppression layer is selected from the group consisting of Fe and Ti.